Prelims
a) R1C12 = {29/38/47/56}, no 1
b) R23C1 = {19/28/37/46}, no 5
c) R23C6 = {69/78}
d) R2C89 = {49/58/67}, no 1,2,3
e) R3C89 = {12}
f) R5C56 = {69/78}
g) R6C12 = {59/68}
h) R67C3 = {16/25/34}, no 7,8,9
i) R67C9 = {59/68}
j) R78C2 = {15/24}
k) 17(2) cage at R7C4 = {89}
l) R89C9 = {19/28/37/46}, no 5
m) R9C23 = {69/78}
n) 8(3) cage at R8C4 = {125/134}
o) 11(3) cage at R8C8 = {128/137/146/236/245}, no 9
Steps resulting from Prelims
1a. Naked pair {12} in R3C89, locked for R3 and N3, clean-up: no 8,9 in R2C1
1b. 8(3) cage at R8C4 = {125/134}, 1 locked for R8 and N8, clean-up: no 5 in R7C2, no 9 in R9C9
1c. Killer pair 8,9 in R8C3 and R9C23, locked for N7
2. 45 rule on R6789 1 innie R6C4 = 3, clean-up: no 4 in R7C3
3. 45 rule on N8 3 innies R7C456 = 22 = {589/679}, no 2,3,4, 9 locked for R7 and N8, clean-up: no 5 in R6C9
4. 45 rule on N3 1 outie R1C56 = 6 = {15/24}
5. 45 rule on N7 2 innies R78C3 = 11 = [29/38], R6C3 = {45}
6. 45 rule on N1 2(1+1) outies R1C4 + R4C2 = 13 = {49/58/67}, no 1,2,3
7. 45 rule on N4 3 innies R4C23 + R6C3 = 12 = {147/246} (cannot be {129} because R6C3 only contains 4,5, cannot be {156} which clashes with R6C12) -> R6C3 = 4, R4C3 = {12}, R4C2 = {67}, R7C3 = 3, R8C3 = 8 (step 5), R7C4 = 9, clean-up: R1C4 = {67} (step 6), no 7 in R9C12, no 2 in R9C9
7a. Killer pair 6,7 in R1C4 and R23C6, locked for N2
8. Naked pair {69} in R9C12, locked for R9 and N7, clean-up: no 4 in R8C9
9. 6 in N8 only in R7C56 = {67} (step 3), locked for R7 and 29(5) cage at R6C5, no 6,7 in R6C5 + R8C7, clean-up: no 8 in R6C9
9a. 8 in N8 only in 15(3) cage at R9C4, locked for R9, clean-up: no 2 in R8C9
10. 24(4) cage at R1C3 = {2679} (only remaining combination), no 1,5, 2,9 locked for C3 and N1 -> R4C3 = 1, R4C2 = 7 (step 7), R1C4 = 6 (step 6), R9C23 = [96], R5C3 = 5, clean-up: no 4,5 in R1C1, no 5 in R1C2, no 1 in R2C1, no 9 in R23C6, no 8 in R3C1, no 9 in R6C1
10a. R8C4 = 1 (hidden single in C4)
11. R23C2 = [15] (hidden pair in N1)
11a. Naked pair {24} in R78C2, locked for C2 and N7, clean-up: no 7 in R1C1
11b. R23C1 = {46} (hidden pair in N1), locked for C1 -> R6C12 = [86], R5C2 = 3, R1C12 = [38], R6C9 = 9, R7C9 = 5, clean-up: no 4,8 in R2C8, no 1 in R9C9
12. R8C7 = 9 (hidden single in N9)
12a. 45 rule on N9 2 remaining innies R7C78 = 10 = {28}, locked for R7 and N9 -> R78C2 = [42]
12b. 8(3) cage at R8C4 = {134} (only remaining combination), locked for R8 and N8
12c. Naked pair {67} in R8C89, locked for R8 and N9
13. Naked pair {78} in R23C6, locked for C6 and N2 -> R7C56 = [76], R5C6 = 9, R5C5 = 6,
R45C1 = [92]
14. 14(3) cage at R5C7 = {148} (only remaining combination), locked for R5 and N6 -> R5C4 = 7
14a. 13(3) cage at R4C7 = {356} (only remaining combination), locked for R4 and N6
15. Naked pair {27} in R6C78, locked for R6 and 18(4) cage at R6C5 -> R7C8 = 8, R6C6 = 1 (cage sum)
16. R4C3 = 1, R56C4 = [73], R3C4 = 4 -> R24C4 = 10 = [28], R1C56 = [15]
17. R2C8 = 5 (hidden single in N3), R2C9 = 8
and the rest is naked singles.